Thanks for the insight Jeff. It pretty much aligns with my suspicions. My thinking was that RQ6 and AiG could have been used as the base for the new RQ but it would have meant sacrificing part of the vision Chaosium had for the new game. The decision was made to maintain the integrity of the vision.
What is the Greg's material you are refering to?
When you mention @too many of our changes", is it a reference to how character creation will be integrated with the background and how the runes will be integrated with characters? I expect these two features to be the highlight of the game (from a mechanic perspective, see below).
I was quite happy to see an "advanced preview" of RQG and I hope the feedback you got guided you to make the game even better. My personal reaction to it was fairly positive with some "darn they kept that rules for RQ2/3 as is.." here and there.
I am a bit surprised that you qualify the announced release dates as "arbitrary guess-timate". Although release dates are probably approximate at best, I would have believed publishers would announced said dates base on "informed planning" and "best available information". That being said, based on what was previewed so far, I expect production value, specifically art, to be the other highlight of the games and I certainly prefer the quality and content to be top notch over "being on time". It certainly is refreshing to know that Chaosium now has the financial resilience to delay a product in order to make it the best it can.

Strangely enough, RuneQuest is probably the game that I have house ruled the most but also, in the 90's, the game I was basing on my house rules to other games. Aside from that, I played many games by the book (Pendragon, Rolemaster, Talislanta, TDE, etc.) and have played both HERO and GURPS as is for decades.
Of course it depends what house ruling means. I personally do not consider house ruling:
1) hand waving (making an executive decision during a game instead of chasing the exact rule in the book)
2) choosing an option in the game instead of another ('the velocity damage rule is made to be easy in play but can be unrealistic at high speed, if you want more realism, use this table instead...")
3) not enforcing a specific rule in a game ("guys don't bother about status/endurance/psionics/whatever, it won't be very important in this game")
Examples of house ruling that I have done:
1) rewriting how the SR pacing works in RQ 3 to make it more tactical and blow-by-blow
2) changing modifiers for combat maneuvers in RQ3 to make them fit into the above
3) adding cultural characteristics modifiers in my Glorantha game (inspired by RQ Viking)
4) adding 3 attributes in MHR and also using d5, d7, d9 and d11

I would put it on the count of over optimism or over enthusiasm. Since the beginning announcements have been made and then reversed and dates and plans have shifted.
"Pete Nash and Lawrence Whittaker are on the design team! Wait, no they're not, welcome Jason Durall. And the game will not be based of RQ6 but on RQ2/RQ3 like we have been saying all along. But the game will still be released for Christmas 2016. Actually no, Gen Con 2017. Well hang on, end of 2017 would be more realistic so let's release a quickstart mid 2017. Darn, finally our big release will be Gen Con 2018."
I believe making the decision to use RQ2/3 as a base instead of RQ6 and the already written Adventure in Glorantha simply inflicted a lot more work on them and since then, they have been doing their best to produce and release as quickly as possible. Please note I do not say this decision was good or bad, I simply observe what I believe was the impact of that decision. The quickstart was released at a time when they still believed they could release the books (at least electronically) by the end of 2017 so in that context, it made sense.
In my opinion they have made some strange decisions along the way and Jeff has made a few statements that rubbed me the wrong way (but again, I will put that on over enthusiasm on his part) but I applaud Chaosium's commitment to communicate through the process.

5th position is not bad. Sure I feel, RuneQuest and Glorantha back together should top the ten games listed but there was some tough competition. I suppose it doesn't help that we almost had Glorantha rejoin RuneQuest about 2 years ago (Pete Nash's manuscript) and then were suppose to see a pre-release version of the new RQ at Gen Con 2016 and that we are now hoping for the book to be released at Gen Con 2018.
Still, I expect it will be worth the wait and that RQG to be the best Glorantha game ever.

I mostly ignored ducks and if I didn't, I definitely used the name Durulz and a visual that is more akin to the one we saw in Hero Wars rather than the Daffy Duck analogue. Another option could have been the barbarian Platypus that is floating around on the web (less the tail). Just search for barbarian platypus on Google.
I mostly played Glorantha in RQ3 so my Glorantha was more down to earth and grittier, very much focused on politico-religious conflicts and searches for ancient mysteries. Magic was less gonzo (no Wind Lords were flying around) and there were no focus at all on the metaphysical.
EDIT I should have added that my Uz are less big hungry savages and more big hungry creature of darkness. Secretive, patient, a bit more sophisticated, scary...

Ignoring setting, my favorire RQ so far is Mythras/RQ6.
1) Characterisrics influence skills in a non clunky way (char+char) and because they are divided between Common and Professional, only basic skills can be used without experience.
2) Better magic systems (different feels yet streamlined)
3) Combat with tactically meaningful choices where, depending on special effect chosen, other skills beside the combat skill influence the outcome.
4) The addition of traits if it floats your boat
5) Rules to support more than fantasy (Firearms, Luther Arkwright, M-Space, Spaceships). The scope of Mythras is simply larger than the other RQs
Again ignoring setting I suspect RQG will be better on the Personality/Passion side and maybe magic but that's it.

Based on previous comments and design notes, my confidence level in how combat will be handle remains very low but I am highly confident in how integrated to Glorantha the character creation will be.
When I see Andrey's intrepretation of Glorantha, I am blown away. I now have very high expectations regarding the production value of this book!

@Paid a bod yn dwp thank you for the link to Jason's post and subsequent explanation. From what I have read so far, it makes sense but will wait to see the final product before passing judgement. My biggest fear right now is that RQG will be a fantastic product from production value, character creation and setting integration perspectives but compared with more modern games, like say Mythras, its combat will feel outdated and clunky. While Jason alleviates some of my fears, I am still not 100% convinced especially in the light of how multiple attacks in melee will work. I thought it was clunky and artificial in the 80s and it still feels that way today. However, I do not want to jump the gun and maybe it will make sense within the whole ruleset.

@David Scott, thanks for the breakdown of character creation and subsequent clarifications. I still hope against all hope that the RQ2 skill modifiers won't be used as is (I am sure easily house ruled to something better) but everything else looks very very promising. Thanks again.